Michmash (2 Nephi 20:28) was a city of Benjamin east of Bethel and 12 kilometers north of Jerusalem, 600 meters above sea level, on the pass from Bethel to Jericho. In Geba, just south of this pass, Jonathan the son of Saul, made a successful foray against the Philistine garrison (1 Samuel 13:3).
In his prophetic description of the coming attack on Jerusalem Isaiah (10:24, 28) represents the taking of Michmash by the Assyrians. [Tyndale House, The Illustrated Bible Dictionary, Vol. 2, p. 997]
2 Nephi 20:28 Michmash ([Illustration]): The location of Michmash, Geba, Gibeah and Bethel in relation to Jerusalem. [Tyndale House, The Illustrated Bible Dictionary, Vol. 2, p. 997]